Saturday, February 16, 2013

Lecturer Physics Past Papers

SPSC,PPSC Lecturer Physics MCQs Past Papers
Sample Papers, Model Papers, Previous Papers of Lecturer Test by Punjab Public Service Commission Lahore for more MCQs of Physics visit here.
(1) If A= 6i-8j, then 4A has the magnitude:
(a) 40 (b) 10  (c) 20  (d) None of these
2)  Let A= 2i+6j-3k and B= 4i+2j+k then A.B equals:
(a) 8i+12j-3k (b) 17  (c) 23  (d) None of these
3) If V is an operator, then V.V means:
(a) Gradient of a Scalar field  (b) Curl of a vector field
(c) Divergence of a Vector field  (d) None of these
4)  The volume of a parallelepiped bounded by Vectors A,B and C can be obtained from the
expression:
(a) ( A x B ).C  (b) (A.B)x C  (c) ( A x B ) x C  (d) None of these
5)  A force acting on a particle is conservative if:
(a) It obeys Newton’s third law  (b) It obeys Newton’s second law
(c) It works equals the change in Kinetic energy (d) None of these
6)  A torque applied to a rigid object always tends to produce:
(a) A rotational acceleration  (b) A linear acceleration
c) Precision  (d) None of these
7)  When the velocity of a body is constant, its acceleration is:
(a) Maximum  (b) Zero  (c) Infinity  (d) None of these
8) In the absence of external torque the total angular momentum is:
(a) Constant (b) Zero  (c) infinity  (d) None of these
9)  The rate of change of Momentum of the particle is:
(a) Energy (b) Force  (c) Impulse  (d) None of these
10)  The intensity of a wave is proportional to the square of:
(a) Amplitude (b) Time  (c) Intensity  (d) None of these
11) The colours in soap bubbles, oil slick etc. in a thin film is due to:
(a) Diffraction  (b) Polaristaion  (c) Interference  (d) None of these
12) For higher resolution, in a diffraction grating, one needs to have:
(a) Large number of ruling  (b) Small number of ruling
(c) No rulings at all  (d) None of these
13) To produce interference, the sources must be:
(a) Intense (b) Incoherent  (c) Coherent  (d) None of these
14) Interference fringes are of:
(a) Unequal width (b) Equal width  (c) Variable width (d) None of these
15) A Carnot Cycle is:
(a) a rectangle on a P-V graph (b) bounded by two isotherms and two adiabatics
(c) any four sided process on a P-V graph (d) None of these
16) In an Adiabatic process:
(a) The temperature of the system remains constant
(b) The temperature of the system must change
(c) The internal energy of the system remains constant
(d) None of these
17) A Carnot Cycle heat engine operates between 227°C and 127° C. Its efficiency is:
(a) 44%  (b) 20%  (c) 79%  (d) None of these
18) Metals pipe carrying water some times bursts in winter because:
(a) Water expands (b) Ice expands when melts
(c) Metal contracts more than water (d) None of these
19) A Fahrenheit thermometer and Celsius thermometer shows the same reading at:
(a) 200° (b) -40°  (c) 100°  (d) None of these
20)  Constructive and destructive superposition of waves is observed in:
(a) Polarisation (b) Interference  (c) Diffraction  (d) None of these
21) A Watt – sec is a unit of:
(a) Force  (b) Energy  (c) Power  (d) None of these
22) The direction of any magnetic induction effect is such as to oppose the cause of the effect. This is:
(a) Coulumb’s Law (b) Ampere’s Law  (c) Lenz’s Law  (d) None of these
23)  A magnetic field cannot:
(a) accelerate a charge (b) Exert a force on a charge
(c) change the kinetic energy of a charge (d) None of these
24)  The inverse of resistivity is called Conductivity. Its unit is:
(a) Ohm-1(b) ohm-metre  (c) (ohm-meter)-1(d) None of these
25  An LRC Circuit has R= 4Ω, Xc = 3 and XL=6, the impedence of the circuit is:
(a) 5 Ω  (b) 7 Ω  (c) 13 Ω    (d) None of these
26)  A “step-down” transformer is used to:
(a) increase the power (b) decrease the voltage (c) Increase the voltage (d) None of these
27) Electrical potential is the potential energy per unit:
(a) Charge (b) Voltage  (c) Force  (d) None of these
28) The force on a charge moving with the velocity in a magnetic field B is given by:
(a) F = (q/v x B)  (b) F = ( qv x B )  (c) F = (qv + B) (d) None of these
29) A changing current “i” in any circuit induces an emf “e” in that circuit, which is equal to:
(a) e = di/dt (b)  E = i dΦ/dt  (c) e = – L di/dt  (d) None of these
30)  Inductive reactance of an inductor is:
(a) XL= ω2L  (b) XL= ω/L  (c) e = -L di/dt  (d) None of these
31) The resonant frequency of an LC-Circuit is:
(a)  f = 2Π LC  (b)  f = 1 / 2Π√ LC  (c) f = 1/ 2LC  (d) None of these
32) The deliberate addition of an impurity element in a semi-conductor is called:
(a) doping  (b) annealing  (c) mixing  (d) None of these
33) The conversion of AC into DC is called:
(a) amplification (b) rectification  (c) modulation (d) None of these
34) The Laser light is:
(a) monochromatic (b) coloured  (c) chromatic  (d) None of these
35) The Laser light may be obtained from:
(a) quartz crystal (b) NaCl crystal  (c) ruby crystal  (d) None of these
36) The emission of photoelectrons in photoelectric effect is dependent on:
(a) threshold frequency (b) intensity of light (c) Nature of metal (d) None of these
37) Which one of the following is NOT needed in Nuclear Fission reactor:
(a) fuel  (b) accelerator  (c) moderator (d) None of these
38) The half life of a radioactive isotope is 140 days. How many days would it take to loose 3/4 of its
initial activities:
(a) 105 days  (b) 280 days  (c) 35 days (d) None of these
39) Most of the energy produced in Sun is due to:
(a) Nuclear fusion (b) Chemical reaction  (c) Nuclear Fission (d) None of these
40) A U-235 nucleus will split when it captures:
(a)  an α-particle (b) e.m. radiation  (c) neutron  (d) None of these
41)  Two particles each of mass 5.0kg are mounted 4.0m apart on a mass-less light rod which is
capable of rotation about its center? The moment of inertia is:
(a) 1.25 kgm2(b) 20 kgm2(c) 40 kgm2(d) None of these
42)  The time period of mass of 1kg attached to a spring of spring constant of 100N/m is:
(a) 0.2π(b)  π(c) 2π(d) None of these
43)  A 14cm inner diameter water main furnishes water (through intermediate pipes) to a 1.00cm inner
diameter faucet pipe. If the average speed in the faucet pipe is 3.0 cm/s, what will be the average
speed it causes in the water main?
(a) 0.015 cm/s (b) 0.15 m/s (c) 0.5 m/s (d) None of these
44)  What is the tension T in the rope if a 10N weight is being pulled upward by it with a constant
velocity of 2m/s?
(a) 12N (b) 8N (c) 5N (d) None of these
45)  The ratio of linear Stress/Linear Strain is called:
(a) Young’s Modulus (b) Bulk Modulus (c) Deformation (d) None of these
46)  A body is moving with constant speed in a circle, its velocity vector:
(a) Remains constant (b) Changes its magnitude (c) Changes its direction
(d) None of these
47)  When a constant torque is acting on a rotating system, which of the following is constant?
(a) Angular velocity (b) Angular acceleration (c) Angular momentum
(d) None of these
48)  A geo-stationary satellite revolves around the earth from:
(a) East to west (b) West to east (c) North to south (d) None of these
49) According to Einstein, with the great i
ncrease in the speed of a body, the relativistic is:
(a) Length remains constant (b) Time decreases
(c) Mass increases (d) None of these
50) A body is moving northward and the force applied is eastward, the acceleration produced is:
(a) Northward (b) At 45oEast of North (c) Eastward (d) None of these

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